1. Technical Field
The present disclosure relates to a method of manufacturing a semiconductor light emitting element having an electrode made of a metal material on a surface of the semiconductor stacked layer body.
2. Description of the Related Art
A semiconductor light emitting element has a semiconductor stacked layer body which is formed by successively stacking an n-type semiconductor layer and a p-type semiconductor layer on a substrate, and is configured to emit light upon applying electric current to the semiconductor stacked layer body. On the semiconductor stacked layer body, electrodes for supplying current are formed, which are then covered with a protective film made of an insulating material for preventing occurrence of short circuit. In manufacturing such a semiconductor light emitting element, a method for simultaneously manufacturing a plurality of elements may be adopted.
Generally, the electrodes of the semiconductor light emitting elements are made of a metal material and formed by using a lift-off method. First, a photoresist is applied to the entire upper surface of the semiconductor stacked layer body and then by using a photolithography method, openings are formed in the photoresist where the electrodes are to be formed. A metal layer is formed on the entire upper surface of the semiconductor stacked layer body and then the metal layer formed on the photoresist is removed by performing lift-off processing. Thus, the electrodes are formed at the predetermined locations.
However, with this method, migration of the material of the electrodes such as Ag may occur at the time of lift-off, resulting in deposition of metal at various locations of the semiconductor stacked layer body. The deposited metal may cause a short circuit between the n-type semiconductor layer and the p-type semiconductor layer, due to metal migration. Thus, metal migration has to be prevented as much as possible. For this reason, a metal such as Ag which is likely to cause migration has been deemed inappropriate as a material for electrodes.
On the other hand, Ag is a material that has both high conductivity and high reflectance, which creates a strong demand for its use as the material of the electrodes in semiconductor light emitting elements, in order to improve the luminous efficiency of the semiconductor light emitting elements.
Accordingly, for example, in a method of manufacturing a semiconductor light emitting element described in JP 2013-171982, the potential difference between the n-type semiconductor layer and the p-type semiconductor layer, which may be a factor in the occurrence of migration, is canceled by causing short-circuit between the n-type semiconductor layer and the p-type semiconductor layer using a conductive material (e.g., a conductor layer). The electrodes are formed in a state where the potential difference is canceled, thus, preventing the migration of the material, such as Ag, of the electrodes.
In the technologies described in JP 2013-197197A, after canceling the potential difference between the n-type semiconductor layer and the p-type semiconductor layer, a conductor layer made of a material such as ITO is removed by etching, thus eliminating occurrence of short-circuit. However, particles of a metal material generated at the time of etching the conductor layer may adhere to the semiconductor light emitting element, which requires further improvement in the method.